Pattern decomposition for directed self assembly patterns templated by sidewall image transfer

Abstract

After forming spacers over a hard mask layer using a sidewall image transfer process, a neutral material layer is formed on the portions of the hard mask layer that are not covered by the spacers. The spacers and the neutral material layer guide the self-assembly of a block copolymer material. The microphase separation of the block copolymer material provides a lamella structure of alternating domains of the block copolymer material.

What is claimed is: 
     
       1. A method of directed self-assembly of a block copolymer material comprising:
 forming spacers on sidewalls of a plurality of mandrels located on a hard mask layer; 
 removing the plurality of mandrels, leaving the spacers protruding from a top surface of the hard mask layer; 
 forming a neutral material layer on exposed portions of the hard mask layer that are not covered by the spacers, wherein the neutral material layer only surrounds a bottom portion of each of the spacers and directly contacts opposite sidewalls of each of the spacers; 
 depositing the block copolymer material onto the neutral material layer and between the spacers; 
 annealing the block copolymer material to form alternating first domains including a first polymer block of the block copolymer material and second domains including a second polymer block of the block copolymer material; and 
 selectively removing the first domains or the second domains, wherein the neutral material layer remains contacting the opposite sidewalls of each of the spacers after the selectively removing the first domains or the second domains. 
 
     
     
       2. The method of  claim 1 , wherein the neutral material layer comprises a material that is chemically neutral to polymer blocks in the block copolymer material. 
     
     
       3. The method of  claim 2 , wherein the neutral material layer is made from a polymer brush material end substituted with a reactive functional group that is capable of bound to the top surface of the hard mask layer. 
     
     
       4. The method of  claim 3 , wherein the polymer brush material is a random copolymer of the polymer blocks of the block copolymer material end substituted with the reactive functional group. 
     
     
       5. The method of  claim 4 , wherein the block copolymer material comprises polystyrene (PS) and poly(methyl methacrylate) (PMMA) (PS-b-PMMA), and the random copolymer comprises PS and PMMA having an OH end group (PS-r-PMMA-OH). 
     
     
       6. The method of  claim 3 , wherein the forming the neutral material layer comprises:
 depositing the polymer brush material over exposed surfaces of the hard mask layer and the spacers; 
 baking the polymer brush material to cause the polymer brush material to bound to the top surface of the hard mask layer; and 
 removing an unreacted portion of the polymer brush material. 
 
     
     
       7. The method of  claim 2 , wherein the neutral material layer comprises a nitrogen-doped silicon carbide, a nitrogen-doped hydrogenated silicon carbide, or combinations thereof. 
     
     
       8. The method of  claim 1 , wherein each of the spacers comprises silicon nitride, and the hard mask layer comprises silicon dioxide or a dielectric metal oxide. 
     
     
       9. The method of  claim 1 , wherein the forming the spacers comprises:
 forming a spacer material layer on exposed surfaces of the plurality of mandrels and the hard mask layer; and 
 removing horizontal portions of the spacer material layer, leaving vertical portions of the spacer material layer on the sidewalls of the plurality of mandrels. 
 
     
     
       10. The method of  claim 1 , wherein a first subset of the second domains is in direct contact with sidewalls of the spacers. 
     
     
       11. The method of  claim 10 , wherein the selectively removing the second domains removes a second subset of the second domains that does not contact the spacers, wherein the first subset of the second domains remains on the sidewalls of the spacers. 
     
     
       12. The method of  claim 11 , wherein the first subset of the second domains has a width equal to one half of a width of the second subset of the second domains. 
     
     
       13. The method of  claim 1 , wherein the hard mask layer comprises a dielectric oxide or a dielectric metal oxide. 
     
     
       14. The method of  claim 1 , wherein the hard mask layer comprises a material that is the same as a material of the neutral material layer. 
     
     
       15. The method of  claim 1 , further comprising forming the plurality of mandrels, wherein the forming the plurality of mandrels comprises:
 forming a mandrel material layer on a top surface of the hard mask layer; and 
 patterning the mandrel material layer to provide the plurality of mandrels. 
 
     
     
       16. The method of  claim 1 , wherein the hard mask layer is formed on a stack of, from bottom to top, a substrate and an organic planarization layer (OPL). 
     
     
       17. The method of  claim 1 , wherein the removing the plurality of mandrels is performed by an oxygen-based plasma etching.